Monitoring the Impact of Vaccination on Pertussis in Infants Using an Active Hospital-based Pediatric Surveillance Network: Results from 17 Years' Experience, 1996-2012, France.

BACKGROUND:Despite a high vaccine coverage in France in children, a resurgence of pertussis in infants too young to be protected by vaccination was observed in the 1990 s, leading to additional vaccination strategies in older age groups. This article describes the epidemiologic trends and characteristics of cases among infants 0-5 months of age during 17 years of pertussis surveillance through Renacoq. METHODS:Renacoq is a sentinel hospital-based voluntary surveillance network covering about 30% of hospitalized pertussis pediatric cases. It includes microbiologists and pediatricians from 42 large hospitals. RESULTS:Since March 1996, the network has described 2227 cases of pertussis in infants aged 0-5 months of whom 67.7% were infants 0-2 months of age. Four epidemic peaks occurred. The estimated national average incidence rate for the children aged 0-2 months decreased significantly between 1996-1998 and 2008-2012 from 264 to 179 per 100,000. Globally, 18.4% of cases were admitted to an intensive care unit, and the average case fatality ratio was 1%. Two-thirds (67.1%) of infants aged 3-5 months were not correctly vaccinated according to age. Parents accounted for 41-57% of the infections and siblings for 17-24%. CONCLUSIONS:Renacoq data confirmed the risk for young children and the need of timely pertussis vaccination. Parents and sibling remain the main source of infection, despite addition of boosters targeting sibling and parents. Improving vaccination coverage in adults in contact with young infants is needed. The continuation of Renacoq surveillance will allow monitoring the impact of additional vaccination strategies.